葡聚糖修饰米根霉脂肪酶条件优化及其稳定性研究

采用经高碘酸钠活化的葡聚糖修饰米根霉脂肪酶，以获得具有较高酸解催化活性的脂肪酶。研究反应时间、反应pH值、还原剂浓度及葡聚糖质量分数对化学修饰效果的影响，并利用Box-Behnken设计法及响应面优化法对米根霉脂肪酶的化学修饰条件进行优化，当反应pH值为7.63、反应时间为15.53 h、还原剂浓度为0.20 mol/L、葡聚糖质量分数为0.3%时，脂肪酶酸解率可达到最高值37.28%。在40 ℃最适温度条件下，修饰酶的活性是原酶的2.2 倍，且经化学修饰后脂肪酶的稳定性有显著提高。

Optimization of Rhizopus oryzae Lipase Modified with Dextran and Its Stability

In order to obtain a high activity of acidolysis, Rhizopus oryzae lipase (ROL) was modified with NaIO4-oxidized
dextran. The effects of reaction time, reaction pH, reductant concentration and dextran concentration on modification
efficiency were studied. Box-Behnken experimental design and response surface methodology were used to optimize the
modification conditions as follows: pH 7.63; reaction time, 15.53 h; reductant concentration, 0.20 mol/L; and dextran
concentration, 0.3%. Under these conditions, the maximum predicted acidolysis rate of lipase of 37.28% was obtained, which
was basically consistent with the experimental value. The effect of the above four factors on the acidolysis rate of lipase
was in the decreasing order of reaction time, reaction pH, dextran concentration and reductant concentration. After chemical
modification, ROL had obvious changes in absorption characteristics in the ultraviolet region. The maximum absorption
wavelength was obviously different. At the optimum temperature of 40 ℃, the activity of dextran-ROL was increased
2.2 times compared to ROL, and the stability of dextran-ROL was also improved significantly.